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Ureteroceles are classified as either intravesical or ectopic. In an intravesical ureterocele, which is also known as a simple ureterocele, the orifice of the ureter and the ureterocele itself are intravesical. The ectopic ureterocele lies in the submucosa of the bladder, and some part of it may extend into the bladder neck or urethra.

Intravesical ureteroceles can be unilateralor bilateral. They are usually diagnosed in adults; hence, they are also called adult-type ureteroceles. They occur more often in women than in men. Ureteroceles are considered congenital by some authorities. Because one of the causes is a narrowed ureteral orifice, however, it is reasonable to conclude that not all unilateral ureteroceles are congenital. Inflammation or trauma leading to fibrosis can cause development of such a ureterocele. Most intravesical ureteroceles are incidental findings in asymptomatic adult patients. When large, ureteroceles can cause obstruction of the bladder neck, along with obstruction of the ipsilateral ureter. This results in an increased frequency of calculus formation, as well as infection. With obstruction, there may be substantial delay in filling the ureter, requiring delayed imaging to make the diagnosis.

Ectopic ureteroceles are almost always seen in association with duplex ureters and arise from the upper-pole ureter. Ureteroceles are usually diagnosed in childhood. Rarely, an ectopic ureterocele occurs without ureteral duplication, usually in boys. Most commonly, the orifice is stenotic, resulting in an obstructed and often nonfunctioning system. An ectopic ureterocele generally appears as an intravesical filling defect instead of the classic cobra head sign.

The cobra head sign is an indicator of an un-complicated ureterocele. However, a cobra-shaped distal end of a ureter may be seen with incomplete distal ureteral obstruction caused by a tumor or calculus. This appearance is termed pseudoureterocele. The appearance of the radiolucent wall surrounding the dilated distal ureteral segment is an important differentiating point between a ureterocele and a pseudoureterocele. The lucency or halo surrounding a pseudoureterocele is thicker than that of a uterocele and is poorly defined; in cases of tumors, it may be irregular and may show a filling defect within the ureterocele. The urographic diagnosis of a pseudoureterocele is much more likely than that of a ureterocele when there is asymmetry of the dilated ureteral lumen, moderate to severe obstruction of the upper tract, and evidence of an acquired cause, such as a calculus or abnormal vesical mucosal pattern. Rarely, thickening of this lucency in a patient with a known ureterocele is usually associated with a complicating process, such as edema with a calculus.

Ultrasonography may demonstrate the wall of the ureterocele projecting into the lumen of the bladder. In questionable cases, cystoscopy may be helpful to rule out a bladder tumor that has formed a pseudoureterocele.

The ivory vertebra sign is seen at conventional radiography and refers to an increase in opacity of a vertebral body that retains its size and contours, with no change in the opacity and size of adjacent intervertebral disks. The increased opacity may be diffuse and homogeneous and involve most or all of the vertebral body, giving it a white appearance as opposed to the normal or possibly osteoporotic appearance of the rest of the vertebral column.

The radiologic finding of a “white” vertebral body is observed in various conditions, each with its own mechanism of producing the classic appearance of the ivory vertebra sign. Osteoblastic metastases elicit a sclerotic response. This stimulation of osteoblasts results in the patchy replacement of vertebral body spongiosa with dense and amorphous bony mass that may become confluent. In a similar manner, certain lymphomatous deposits elicit marked osteoblastic response in the spongiosa, thereby resulting in bone formation and diffuse homogeneous sclerotic change. These lymphomatous foci involve the vertebral body through either hematogenous spread or contiguous invasion from adjacent lymph nodes. Another explanation is Paget disease, a condition in which simultaneous atrophy of the spongiosa and coursening of the vertical trabeculae can simulate an ivory vertebra.

Paget disease, however, usually causes expansion of the vertebral body contour, thereby limiting the ability of a vertebra affected by Paget disease to fully conform to the definition of an ivory vertebra. Reactive bone formation that occurs in response to stress on weakened bone, similar to the way a callus develops in a healing fracture, can give the appearance of an ivory vertebra; this process is termed idiopathic segmental sclerosis.

The ivory vertebra sign can be seen in both adults and children. In children, the finding is much less common and is typically the result of lymphoma, usually Hodgkin lymphoma. Even less frequently, children may have osteosarcoma, metastatic neuroblastoma, medulloblastoma, or osteoblastoma that involves a vertebral body and causes increased opacity. A few cases of Ewing sarcoma with dense vertebral bodies have been reported. In such cases, while the tumor itself is lytic, the reactive bone formation can be exceptionally opaque.

In adults, numerous conditions are responsible for the appearance of an ivory vertebra. Traditionally, the ivory vertebra sign has been associated with metastatic disease, especially carcinoma of the prostate or breast, and occasionally with osteosarcoma, carcinoid, Paget disease, and lymphoma, particularly Hodgkin lymphoma.

Carcinoma of the breast or prostate commonly results in osteoblastic metastases. A radiopaque vertebral body at one or more vertebral levels in an elderly man is most compatible with a diagnosis of metastatic disease, commonly as the result of prostate carcinoma. Other metastatic tumors, including lymphoma, must be considered along with more rare lesions, such as plasmacytoma, chordoma, or primary bone sarcomas. Metastatic cancer involving the spine usually manifests at several vertebral levels; however, solitary lesions in patients with breast carcinoma are not uncommon.

Lateral radiograph shows uniformly increased opacity of entire T7 vertebra (arrow), with retention of vertebral body size and contour. Incidental note is made of loss of height at T8 vertebra.

Paget disease can give the appearance of an ivory vertebral body, but, more often, the disease is characterized by the “picture frame” vertebral body. The “picture frame,” “double contour,” or “windowed” vertebral body of Paget disease shows increased overall opacity, with sclerosis most marked at the periphery, and a relatively lucent center owing to atrophy of the spongiosa. The trabecular bone is thickened, and increased anteroposterior and lateral dimensions result in overall bone expansion. In Paget disease, the increased size of the vertebral body is a distinct appearance and usually allows differentiation of this disease from the other causes of the ivory vertebra sign.

Paget disease occurs in an older age group and is usually polyostotic. It has been suggested that idiopathic ivory vertebra, which is defined as an ivory vertebra for which no apparent cause is found and for which the appearance remains unchanged over time, may be attributable to asymptomatic Paget disease of bone. Definitive histologic evidence of the condition, however, is lacking.

Osteomyelitis is known to produce sclerosis in a vertebra during the healing phase, but this condition rarely involves a single vertebra. Usually, erosive change is present at the margins of the intervertebral disk and helps to guide diagnosis.

The ivory vertebra sign has numerous causes. While clinical settings will vary, and a list of causes is available, most causes of the ivory vertebra sign are rare. In adults, three conditions should generally be considered: metastatic cancer, Paget disease, and lymphoma.

At radiography, sclerotic bands along the superior and inferior thoracic and lumbar vertebral body endplates give a striped appearance to the vertebral bodies, with a relative band of lucency at the center of each vertebral body. The alternating parallel sclerotic and lucent bands are analogous to the stripes on an English rugby sweater, from which arises the name “rugger jersey spine”.

The opaque sclerotic bands seen on the inferior and superior endplates of vertebral bodies represent accumulations of excess osteoid. Although they are deficiently mineralized, the areas of osteoid appear opaque at radiography because of their increased volume in comparison with that of normal bone. The spinal canal and intervertebral disk spaces are normal.

Lateral radiograph of the thoracic spine in a patient with chronic renal failure. The image shows band-like regions of increased opacity at the superior and inferior margins of the vertebral bodies, which is typical of the rugger jersey spine sign.

The rugger jersey spine sign is said to be almost DIAGNOSTIC OFtheosteosclerosis associated with secondary hyperparathyroidism of chronic renal failure. The major skeletal components of renal osteodystrophy that can be seen on radiographs include osteomalacia, osteosclerosis, and soft-tissue calcification. Osteomalacia is defined as bone that contains insufficient or delayed mineralization of osteoid tissue. In children, osteomalacia secondary to renal disease may manifest as rickets. In adults, osteomalacia as a result of renal osteodystrophy may manifest as osteopenia, a decrease in bone density. Renal osteodystrophy may manifest radiographically as subperiosteal resorption of bone in the radial aspect of the middle phalanges of the hand. This process later manifests radiographically as areas of resorption in concave areas such as the proximal tibia and femoral neck. In contrast, osteosclerosis due to renal osteodystrophy tends to predominate in the axial skeleton, most commonly manifesting in the pelvis, ribs, and spine. Osteosclerosis occurs in about 20% of patients with chronic uremia and renal osteodystrophy.

Renal transplantation paradoxically worsens osteodystrophy, and steroids necessary to prevent transplant rejection accentuate osteoporosis and can cause ischemic necrosis of the femoral heads. In addition, secondary hyperparathyroidism can continue after renal transplantation. Tertiary hyperparathyroidism may develop, an entity in which the parathyroid glands develop autonomous control, which results in persistent bone resorption and hypercalcemia.

Other disease processes may mimic the rugger jersey spine sign. Paget disease, osteoporosis, metastatic lesions, or osteomalacia are the diseases that have radiographic appearances that are commonly confused with the rugger jersey spine.

One factor to keep in mind when differentiating spinal dystrophic findings is that the rugger jersey spine sign is multi-segmental, as it affects multiple vertebral bodies. The bands of increased opacity along the superior and inferior aspect of the vertebral bodies differ from the uniformly increased opacity seen in Paget disease, skeletal metastasis, or lymphoma. Skeletal metastasis and lymphoma produce the so-called ivory vertebral body, and these diseases may affect a solitary vertebral body.

The rugger jersery spine sign can be differentiated from the “picture frame” vertebral body seen with Paget disease. The cortex of the vertebral body is thickened in a patient with Paget disease. This is a result of disorganized new cortical bone formation after excessive osteoclastic activity causes the resorption of normal bone. At radiography, this results in increased opacity of the cortex on ALL sides of the vertebral body, whereas the characteristic sclerosis of the rugger jersey spine is seen only at the superior and inferior endplates.

Lateral radiograph of the lower thoracic and lumber spine in a patient with Paget disease showing the "frame picture".

The appearance of osteoporotic vertebral bodies can vary and at times may mimic that of osteosclerosis. Osteoporosis most frequently results in wedging and compression of the vertebral bodies. Osteoporosis can result in concavity of the superior and inferior endplates. These appearances are caused by diffuse weakening of the bone and occur most commonly in the thoracic and lumbar spine. Trabecular thinning, which is usually seen in the middle to upper thoracic spine, leads to relative radiographic opacity of the superior and inferior endplates.

Other generalized disease processes that seemingly imitate the rugger jersey spine sign include fluorosis and myelofibrosis. Fluorosis and myelofibrosis involve the axial skeleton and result in increased opacity of the vertebral bodies, pelvis, and bones of the thorax. Diffuse findings such as ligamentous calcification, periostitis, and vertebral osteophytosis differentiate fluorosis from renal osteodystrophy. Myelofibrosis is associated with splenomegaly and cortical thinning of long bones. A complete skeletal survey, in addition to pertinent clinical and laboratory data, aids in distinguishing these disorders.

The football sign, which is seen on supine abdominal radiographs, refers to a large oval radiolucency in the shape of an American football. The long axis of the “football” runs cephalocaudad, and the blunted ends are defined by the diaphragm and pelvic floor. A well-defined and vertically oriented linear opacity may be identified within the cephalic portion of the radiolucency, overlying the right upper abdomen. An additional, well-defined and vertically oriented linear opacity may be seen within the caudal portion of the radiolucency, overlying the midline of the lower abdomen.

The oval radiolucency seen in the football sign represents massive pneumoperitoneum, which distends the peritoneal cavity. In the supine position, free air collects anterior to the abdominal viscera, producing a sharp interface with the parietal peritoneum and thereby creating the football outline. The pneumoperitoneum may outline the falciform ligament, which is seen as a faint linear opacity situated longitudinally within the right upper abdomen.

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Also, the massive pneumoperitoneum may outline the median umbilical ligament, which comprises the urachal vestige, or may outline the medial and lateral umbilical ligaments, which comprise the umbilical arteries and inferior epigastric vessels, respectively. Similar to the appearance of the falciform ligament, these anterior abdominal body wall structures may be visualized as faint longitudinal linear opacities in the midline of the lower abdomen. Some authors describe these anterior abdominal wall structures as necessary components of the football sign; they represent the seams or laces of an American football.

Anteroposterior supine abdominal radiograph shows the football sign in a neonate with rectal perforation secondary to traumatic placement of a rectal tube. Pneumoperitoneum is seen as a large oval radiolucency demarcated by the parietal peritoneum of the abdominal wall (curved arrows). The falciform ligament (straight arrows) is outlined by air.

Conditions that result in a degree of pneumoperitoneum sufficient to create the football sign occur most commonly in infants. Massive pneumoperitoneum is much less common in adults and older children. In part, this may relate to the improved ability of older patients to communicate their abdominal symptoms, which leads to earlier intervention. A small-to-moderate volume of pneumoperitoneum in an adult may be inadequate to produce the football sign, but this may represent a relatively large amount of free air in a small infant.

Although the source of pneumoperitoneum may vary, the football sign is most frequently encountered in infants with spontaneous or iatrogenic gastric perforation. In many cases of perforated small bowel or perforating appendicitis, there is little to no pneumoperitoneum identified, which is likely because of the localized inflammatory process surrounding the perforation.

Other causes of pneumoperitoneum in neonates include necrotizing enterocolitis, bowel obstruction (i.e. malrotation with midgut volvulus, Hirschsprung disease, meconium ileus, or atresia), and sources of inflammation such as gastric or duodenal ulcers. Mechanical ventilation causing barotrauma and extra-ventilatory air can extend beneath the diaphragm, resulting in pneumoperitoneum without gastrointestinal perforation.

In most cases, the football sign in infants isDIAGNOSTICofgastrointestinal perforation, and NO further imaging is necessary. With smaller quantities of extraluminal air, the football sign may be absent, and other features, such as air on both sides of the bowel wall or localized radiolucency, may be seen. Either left lateral decubital or cross-table lateral views are standard in assessment for pneumoperitoneum.

The football sign, seen at supine abdominal radiography, refers to a large oval radiolucency that represents a large amount of pneumoperitoneum in the shape of an American football. The ovoid appearance is the acknowledged hallmark of the football sign. Ancillary findings, including visualization of the falciform ligament or the umbilical ligaments, are also confirmatory of pneumoperitoneum and have been variously included in descriptions of this sign.

The dripping (or flowing) candle wax sign is seen on conventional radiographs depicting bone. The appearance is that of irregular cortical hyperostosis, typically occurring on one side of the involved bone, and has been likened to melted wax flowing down one side of a candle.

The dripping candle wax sign indicates melorheostosis. The radiographic findings may reflect a developmental error primarily in intramembranous bone formation. This leads to an irregular thickening of cortical bone (cortical hyperostosis) that extends up to (but usually not past) the articular surface. Pathologic findings suggest both overproduction of bone matrix and increased angiogenesis. The distribution of affected bone is thought to be due to the predilection of melorheostosis to occur in sclerotomes (skeletal regions innervated by a single spinal sensory nerve).

Note irregular flowing hyperostosis (arrows) along caudal surface of the eighth and ninth right posterior ribs.

Melorheostosis (also known as Leri disease) is a rare sclerosing bone dysplasia. The name is derived from the Greek words for limb (melos) and flow (rhein), due to its characteristic appearance of flowing hyperostosis. Patients are often asymptomatic, with the condition diagnosed as an incidental finding on radiographs obtained for another purpose.

When melorheostosis does manifest clinically, the most common presentation is of limb stiffness or pain. Although the age at presentation varies, it usually remains occult until late adolescence or early adulthood. The disease follows a chronic progressive course, occasionally resulting in substantial disability that may lead to amputation.

Melorheostosis predominantly affects the appendicular skeleton and is most common in the long bones of the upper and lower extremities, although it can be seen in the hands and feet as well. Melorheostosis has rarely been reported in the axial skeleton. It may affect a single bone (monostotic), a single limb (monomelic), or multiple bones (polyostotic).

Ludwig’s angina denotes cellulitis of the floor of the mouth with infection of
the submental, sublingual, and submandibular space. This infection is usually
due to streptococcus or staphylococcus species. Patients usually present with
pain, tenderness and swelling of the mouth floor. The infection is usually
precipitated by an odontogenic infection. In neglected cases, Ludwig’s angina may
spread inferiorly through fascial planes into the mediastinum, with some
patients presenting with chest pain. Since the tongue can rapidly become posteriorly displaced in this condition,
securing a patient’s airway is a priority.

Contrast-enhanced CT shows swelling of the floor of the mouth frequently
associated with streaky changes in the adjacent subcutaneous fat and thickening
of the overlying platysmus muscle. Enlargement of the submental or submandibular
lymph nodes may also be seen, with pus or gas formation present in late cases.

Contrast enhanced MR images, if performed, may show a
thickened floor of the mouth with strong enhancement. On T2-weighted images,
diffuse high signals are evident in the floor of the mouth and adjacent soft
tissues.

An abscess in the parapharyngeal space may arise from direct extension of
infection from the pharynx through the pharyngeal wall, as a consequence of
odontogenic infection, local trauma, and occasionally peritonsillar
abscess. Diabetes is the most common systemic condition
predisposing one to parapharyngeal abscess.

Patients often present with fever, sore throat and neck swelling. Erythema,
odynophagia, and dysphagia often accompany such infections. Trismus
is most commonly associated with anterior compartment abscesses.

Contrast-enhanced CT scanning is the imaging examination of choice to diagnose
parapharyngeal abscess. CT shows a single or multiloculated low-density lesion
with an air and/or fluid center with occasional enhancement of the abscess wall.

Rasmussen encephalitis is a chronic, progressive inflammation of the brain of
un-known origin. The onset is in childhood and is characterized by an abrupt
appearance of focal, persistent motor seizure activity (epilepsia partialis
continua), followed by hemiplegia and progressive cognitive deterioration. Early
diagnosis and treatment with immunoactive agents or hemispherectomy are sought
to prevent the cognitive decline. A hypothesis of the pathogenesis is glutamate
receptor autoimmunity associated with persistent viral infection. This receptor activation may trigger seizures in these
patients.

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CT and MRI Images of All patients display cortical atrophy associated with ipsilateral ventricular enlargement and caudate atrophy, more severe in those with hemiparesis. The most affected areas were insular, temporal and parietal regions. Gray and white matter focal signal intensity abnormalities (hyperintense signal in long TR-weighted images) were found in with hemiparesis.

Histopathologic examination of biopsy material reveals a characteristic triad of
findings: perivascular lymphocytic cuffing of round cells, gliosis and
microglial nodules. CT and MRI demonstrate progressive destruction of a single
cerebral hemisphere. Decreased NAA and elevation of
glutamate/glutamine levels on MRS are reported.

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MRS performed showed increased lactate and choline and decreased NAA in atrophic regions in a patient with Rasmussen's Encephalitis.

A Bezold abscess is a rare complication of otomastoiditis with necrosis of the
mastoid tip and spread of infection from bone to the adjacent soft tissue.
Inflammatory collections may course along the plane of the sternocleidomastoid
muscle to the lower neck. If left untreated, the abscess may spread as far as
the larynx and mediastinum, which results in a poor prognosis. Clinically,
patients present with fever, neck pain, restricted neck motion, and otalgia. Due to the close proximity to the internal jugular vein, internal jugular vein thrombosis is a recognised commonly associated complication.

On CT imaging, there is usually unilateral opacification of the middle ear and
mastoid cavities, often associated with bone erosion, especially of the mastoid
tip.
The abscess involves the adjacent musculature surrounding the mastoid and
extends inferiorly.

Axial Computed Tomography of the chest reveals a small hyperlucent left lung with atresic vascular structures and evidence of air trapping characteristic of the Swyer-James syndrome.

The condition was first described in Canada in the 1950s by :

Paul Robert Swyer : English paediatrician in Canada,

William Mathieson MacLeod : English pulmonologist (1917 - 1977),

George C. W. James : Canadian radiologist.

It has also been referred to asMacLeod syndrome, but this is not advised to be used du to the presence of a rare genetic syndrome resulting in slowly progressive degeneration of a variety of tissues including blood, brain, peripheral nerves, muscle and heart - bearing a very closely similar name: McLeod syndrome.

Swyer-James syndrome (SJS) is a manifestation of postinfectious obliterative bronchiolitis. In SJS, the involved lung or portion of the lung does not grow normally and is slightly smaller than the opposite lung. The characteristic radiographic appearance is that of pulmonary hyperlucency, caused by overdistention of the alveoli in conjunction with diminished arterial flow.

Plain X-ray Chest revealed the left lung is smaller and more lucent compared to the right. In addition, the
pulmonary vessels on the left are smaller and don't extend as far peripherally
as those on the right.

For patients with Swyer-James syndrome, chest computed tomography (CT) scanning with thin collimation sections on inspiration and expiration is the preferred examination. The appearance of the lungs on forced expiration is important in the assessment of SJS with CT scanning; therefore, the patient's co-operation is essential. The patient should be placed in the prone position to help identify the typical mosaic pattern of the syndrome.

In Swyer-James syndrome, the bronchi have a pruned appearance. A mosaic pattern of air trapping in acini is seen, along with air trapping during expiration. The appearance is similar to that of hypoplastic lung syndrome. In addition, the appearance of Swyer-James syndrome is the same as that of bronchiolitis obliterans, but bronchiolitis obliterans is more frequently a diffuse process.

CT aids in the differential diagnosis between SJS, bronchial obstruction and congenital vascular anomalies like unilateral pulmonary artery agenesis or scimitar syndrome, showing preserved anatomy of tracheobronchial tree and pulmonary arteries. Currently available post-processing tools improve MDCT diagnostic performances; in particular the combination of multiplanar reformatted images with maximum intensity projection (MIP) is most effective in vascular imaging while minimum intensity projection (minIP) reconstructions help to disclose differences in lung attenuation and depiction of bronchial structures.

In Asian philosophy, the concept of yin yang (simplified Chinese: 阴阳; traditional Chinese: 陰陽; pinyin: yīnyáng), which is often referred to in the West as "yin and yang", is used to describe how polar opposites or seemingly contrary forces are interconnected and interdependent in the natural world, and how they give rise to each other in turn. Opposites thus only exist in relation to each other. The concept lies at the origins of many branches of classical Chinese science and philosophy, as well as being a primary guideline of traditional Chinese medicine, and a central principle of different forms of Chinese martial arts and exercise, such as baguazhang, taijiquan (t'ai chi), and qigong (Chi Kung) and of I Ching divination. Many natural dualities — e.g. dark and light, female and male, low and high, cold and hot — are thought of as manifestations of yin and yang (respectively).

Yin yang are not opposing forces (dualities), but complementary opposites that interact within a greater whole, as part of a dynamic system. Everything has both yin and yang aspects as light cannot exist without darkness and vice-versa, but either of these aspects may manifest more strongly in particular objects, and may ebb or flow over time. The concept of yin and yang is often symbolized by various forms of the Taijitu symbol, for which it is probably best known in western cultures.

Yin Yang is represented by the Taijitu symbol, which is a diagram of the supreme Ultimate. It is a circle divided into two teardrop shaped halves, one white, the other black, each containing a small circle of the opposite colour.

There is a perception (especially in the West) that yin and yang correspond to evil and good. However, Taoist philosophy generally discounts good/bad distinctions and other dichotomous moral judgments, in preference to the idea of balance. Confucianism did attach a moral dimension to the idea of yin and yang, but the modern sense of the term largely stems from Buddhist adaptations of Taoist philosophy.

Meigs syndrome is defined as the triad of benign ovarian tumor with ascites and pleural effusion that resolves after resection of the tumor. The ovarian tumor in Meigs syndrome isa fibroma.

In 1934, Salmon described the association of pleural effusion with benign pelvic tumors. In 1937, Meigs and Cass described 7 cases of ovarian fibromas associated with ascites and pleural effusion. In 1954, Meigs proposed limiting true Meigs syndrome to benign and solid ovarian tumors accompanied by ascites and pleural effusion, with the condition that removal of the tumor cures the patient without recurrence. Histologically, the benign ovarian tumor may be a fibroma, thecoma, cystadenoma, or granulosa cell tumor.

Pseudo-Meigs syndrome consists of pleural effusion, ascites, and benign tumors of the ovary other thanfibromas. These benign tumors include those of the fallopian tube or uterus and mature teratomas, struma ovarii, and ovarian leiomyomas. This terminology sometimes also includes ovarian or metastatic gastrointestinal malignancies.

Meige's syndrome:

It is a type of dystonia. It is also known as Brueghel's syndrome and oral facial dystonia. It is actually a combination of two forms of dystonia, blepharospasm and oromandibular dystonia (OMD).When OMD is combined with Blepharospasm, it may be referred to as Meige’s Syndrome named after Henri Meige, the French neurologist who first described the symptoms in detail in 1910. The symptoms usually begin between the ages of 30 and 70 years old and appear to be more common in women than in men (2:1 ratio). The combination of upper and lower dystonia is sometimes called cranial-cervical dystonia.

The drooping lily sign can be identified at excretory urography in patients with duplicated renal collecting systems. The sign consists of inferolateral displacement of a functioning lower pole moiety and lateral displacement of the most superior calices of the lower pole collecting system, usually by a nonopacified, hydronephrotic upper pole collecting system. The appearance of the lower pole collecting system is reminiscent of a lily flower that is wilting or drooping.

Radiograph obtained at excretory urography in a 1-month-old female patient in the supine position demonstrates inferior and lateral displacement of the lower pole moiety (arrow) of a right duplicated collecting system: the drooping lily sign. The left collecting system is normal.

The drooping lily sign is due to inferior and lateral displacement of the lower pole moiety of a duplex kidney, rather than displacement of an entire kidney. An obstructed, poorly functioning upper pole moiety exerts a mass effect on the lower pole collecting system, which is responsible for the abnormal axis of the lower pole calices and which causes the droop of the lily. Because only the lower pole collecting system is opacified with intravenously administered contrast material, a decreased number of calices are depicted, as no calices extend cephalad from the renal pelvis.

The sign is often accompanied by a bladder filling defect, representing a ureterocele, which is associated with the ectopic insertion of the upper moiety ureter. As the frequency of excretory urography wanes, the “classic” drooping lily is less frequently encountered. Diagnostic consideration should be given to the presence of a duplication anomaly whenever a process is discovered in only one portion of a kidney.

The lemon sign refers to the shape of the fetal skull at ultrasonography (US) when the frontal bones lose their normal convex contour and appear flattened or inwardly scalloped. This gives the skull a shape similar to that of a lemon. The sign is seen on transverse sonograms of the fetal cranium obtained at the level of the ventricles.

Transverse cranial sonogram of a 20-week-old fetus with spina bifida. Image obtained at the level of the ventricles demonstrates the lemonlike configuration of the fetal skull due to biconcavity (arrows) of the frontal bones.

Transverse cranial sonogram of an 18-week-old fetus demonstrates the normal contour of a fetal skull.

The lemon sign has a strong association with spina bifida. Although the exact pathogenesis is unknown, it has been postulated that the decrease in the intraspinal pressure in neonates with spina bifida causes the brain to shift downward. This shift decreases the intracranial pressure, which is reflected onto the fetal cranium. The frontal bones are the most vulnerable to the decreased intracranial pressure and respond by flattening or scalloping inward.

As the fetus matures, the lemon sign disappears because the frontal bones become stronger and are able to withstand the decreased pressure. In addition, the majority of neonates with spina bifida develop hydrocephalus as they mature. This increase in intracranial pressure can lead to reversal of the flattening. However, this theory does not explain why the lemon sign is present in fetuses with a normal posterior fossa.

Therefore, an alternative theory has been proposed that the lemon sign might be due to a primary skeletal developmental disorder and that the contour of the skull is a result of mesenchymal dysplasia of the cranium.

The lemon sign is very useful in the detection of spina bifida in a high-risk population before 24 weeks of gestation. The lemon sign is not exclusive to spina bifida. It has been seen in a variety of conditions such as encephalocele, Dandy-Walker malformation with encephaloceles, thanatophoric dysplasia, cystic hygroma, diaphragmatic hernia, agenesis of the corpus callosum, fetal hydronephrosis, and umbilical vein varix and two-vessel cord.

Detection of the spinal defect by using prenatal US can be very difficult and depends on the experience and skill of the sonographer. The spinal defect may be detected approximately 80% of the time when the examination is performed by a highly qualified sonographer who is carefully evaluating the spine. In contrast, the sensitivity for detection of a spinal lesion is lower than 50% when US is performed in a low-risk population, by an inexperienced sonographer, or by using less-advanced equipment.

The lemon sign is a useful tool to aid in the detection of spina bifida. Detection of the lemon sign does not require the high level of skill that is needed for US evaluation of the spine. If the lemon sign is present, this should signal the possibility of spina bifida and should prompt the sonographer to look for other cranial markers of spina bifida and to perform a more detailed evaluation of the spine.

While doing your regular breast self-examamination of youe breasts, you may feel a breast fibroadenoma. Women sometimes refer to them as “breast mice” because they tend to run away from fingers while examening the breast.

Fibroadenomas of the breast, are lumps composed of fibrous and glandular tissue. Because breast cancer can also appear as a lump, doctors may recommend a tissue sample (biopsy) to rule out cancer in older patients. Unlike typical lumps from breast cancer, fibroadenomasare easy to move, with clearly defined edges.

Ultrasound appearance of the mass which is oval, measured about 10 x 5 mm. and showed smooth margins which
were well defined. The lesion was non-calcific and seemed extremely mobile on
probe pressure.

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Power Doppler image shows poor vascularity of the lesion.

The typical case is the presence of a painless, non-tender although may get tender especially right before the menstrual period, when it may swell due to hormonal changes, firm, solitary, freely mobile, slowly growing lump in the breast of a woman of childbearing years. A fibroadenoma is usually diagnosed through clinical examination, ultrasound or mammography, and often a needle biopsy sample of the lump may be recommended.

Fibroadenomas arise in the terminal duct lobular unit of the breast. They are the most common breast tumor in adolescent women. They also occur in a small number of post-menopausal women. Their incidence declines with increasing age, and, in general, they appear before the age of thirty years. Fibroadenomas are partially hormone-dependent and frequently regress after menopause. They are hypovascular compared to typical (especially malignant) neoplasms.

The Mount Fuji sign is a finding that can be observed on computed tomographic (CT) scans of the brain, in which bilateral subdural hypoattenuating collections cause compression and separation of the frontal lobes. The collapsed frontal lobes and the widening of the interhemispheric space between the tips of the frontal lobes have the appearance of the silhouette of Mount Fuji—hence, the Mount Fuji sign.

A photo of The Mount Fuji.

Unenhanced transverse CT image of the brain demonstrates bilateral subdural areas of hypoattenuation (∗) with compression of the frontal lobes.

Unenhanced transverse CT image of the brain obtained caudal to image shown in previous figure. Widening of the interhemispheric space between the tips of the frontal lobes is noted. The medial surface of each frontal lobe is marked (arrows).

The hypoattenuating collections are caused by the entry of air into the cranial vault, a condition that can occur in iatrogenic and noniatrogenic disruption of the skull base or calvaria. However, tension pneumocephalus (i.e, subdural air causing mass effect on the brain) requires conditions that lead to increased air pressure within the subdural space. The increased pressure of air is assumed to be due to a ball-valve mechanism. This implies that air enters into the subdural space by means of a dehiscence in the skull base or calvaria and that the egress of air is blocked by an obstruction. An additional mechanism (ie, posterior fossa surgery in the sitting position) has been postulated, but it was later discredited. In these cases, it was believed that nitrous oxide, which was used as an anesthetic, diffused into air-filled spaces and expanded the gaseous volume. Irrespective of the mechanism, the increased pressure may lead to extra-axial mass effect with subsequent compression of the frontal lobes. The presence of air between the frontal tips suggests that the pressure of the air is at least greater than that of the surface tension of cerebrospinal fluid between the frontal lobes.

The Mount Fuji sign on CT scans of the brain is useful in discriminating tension pneumocephalus from nontension pneumocephalus. Tension pneumocephalus canbeconsidereda neurosurgical emergency, unlike nontension pneumocephalus. Tension pneumocephalus occurs most commonly after the neurosurgical evacuation of a subdural hematoma.

The Mount Fuji sign on CT scans of the head in trauma patients and in postoperative patients can be a critical finding made by the radiologist. Identification of this sign can have immediate and important clinical implications for patient care and outcome.

The golf ball–on-tee sign is seen during excretory urography and appears as a contrast agent–filled cavity (the golf ball) that lies adjacent to a blunted calyx (the tee).

Excretory urogram (frontal view) displaying the left side of the collecting system shows contrast material in a large papillary cavity, the “golf ball” (∗). A blunted calyx, the “tee,” is adjacen (arrow).

Photograph of a golf ball on a tee.

The collecting tubules within the medullary pyramid come together to form the papillary ducts that penetrate the papillary tip and drain into a calyx. Normally, individual collecting tubules are not visualized; rather, the normal papilla has a distinctive blush that fades with time. In papillary necrosis, however, central necrosis and sloughing of the papilla create a cavity, which is occasionally large, that fills with contrast material and communicates with the calyceal concavity. Thus, the golf ball–on-tee sign is created, indicating necrosis.

The common etiology of papillary necrosis can be conveniently remembered with Dunnick's mnemonic NSAID: nonsteroidal anti-inflammatory medications, sickle cell hemoglobinopathies, analgesic nephropathy (specifically aspirin and phenacetin), infection (specifically tuberculosis), and diabetes. Some less-common causes include renal vein thrombosis, hypotension, and obstructive uropathy. The papillary necrosis seen in tuberculosis and severe pyelonephritis is a direct result of the infection.